feat(slider): add fullWidth prop (#1354)

The `bx--slider` class in the `Slider` component has max-width of `40rem`. Because `$$restProps` is spread to the top-level `div` element in `Slider`, the only way to override the style is to do so globally:

```css
:global(.bx--slider-container) {
  width: 100%;
}

:global(.bx--slider) {
  max-width: none;
}
```

This adds a `fullWidth` prop that sets a full width style using inline style attributes.

types/Slider/Slider.svelte.d.ts

@@ -75,6 +75,13 @@ export interface SliderProps
    */
   hideTextInput?: boolean;
 
+  /**
+   * Set to `true` for the slider to span
+   * the full width of its containing element.
+   * @default false
+   */
+  fullWidth?: boolean;
+
   /**
    * Set an id for the slider div element
    * @default "ccs-" + Math.random().toString(36)